science

Human error assessment and reduction technique

Human error assessment and reduction technique is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Human error assessment and reduction technique rather than just read about it. In short: Human error assessment and reduction technique (HEART) is a technique used in the field of human reliability assessment (HRA), for the purposes of evaluating the probability of a human error occurring throughout the completion of a specific task. From such analyses measures can then be taken to reduce the likelihood of errors occurring within a system and therefore lead to an improvement in the overall levels of saf…

Key takeaways

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Reference excerpt

Human error assessment and reduction technique (HEART) is a technique used in the field of human reliability assessment (HRA), for the purposes of evaluating the probability of a human error occurring throughout the completion of a specific task. From such analyses measures can then be taken to reduce the likelihood of errors occurring within a system and therefore lead to an improvement in the overall levels of safety. There exist three primary reasons for conducting an HRA: error identification, error quantification, and error reduction. As there exist a number of techniques used for such purposes, they can be split into one of two classifications: first-generation techniques and second generation techniques. First generation techniques work on the basis of the simple dichotomy of 'fits/doesn't fit' in the matching of the error situation in context with related error identification and quantification and second generation techniques are more theory based in their assessment and quantification of errors. HRA techniques have been used in a range of industries including healthcare, engineering, nuclear, transportation, and business sectors. Each technique has varying uses within different disciplines. HEART method is based upon the principle that every time a task is performed there is a possibility of failure and that the probability of this is affected by one or more Error Producing Conditions (EPCs) – for instance: distraction, tiredness, cramped conditions etc. – to varying degrees. Factors which have a significant effect on performance are of greatest interest. These conditions can then be applied to a "best-case-scenario" estimate of the failure probability under ideal conditions to then obtain a final error chance. This figure assists in communication of error chances with the wider risk analysis or safety case. By forcing consideration of the EPCs potentially affecting a given procedure, HEART also has the indirect effect of providing a range of suggestions as to how the reliability may therefore be improved (from an ergonomic standpoint) and hence minimising risk.

Background HEART was developed by Williams in 1986. It is a first generation HRA technique, yet it is dissimilar to many of its contemporaries in that it remains to be widely used throughout the UK. The method essentially takes into consideration all factors which may negatively affect performance of a task in which human reliability is considered to be dependent, and each of these factors is then independently quantified to obtain an overall Human Error Probability (HEP), the collective product of the factors.

HEART methodology 1. The first stage of the process is to identify the full range of sub-tasks that a system operator would be required to complete within a given task. 2. Once this task description has been constructed a nominal human unreliability score for the particular task is then determined, usually by consulting local experts. Based around this calculated point, a 5th – 95th percentile confidence range is established. 3. The EPCs, which are apparent in the given situation and highly probable to have a negative effect on the outcome, are then considered and the extent to which each EPC applies to the task in question is discussed and agreed, again with local experts. As an EPC should never be considered beneficial to a task, it is calculated using the following formula:

Calculated Effect = ((Max Effect – 1) × Proportion of Effect) + 1 4. A final estimate of the HEP is then calculated, in determination of which the identified EPC's play a large part. Only those EPC's which show much evidence with regards to their affect in the contextual situation should be used by the assessor.

Worked example

Context A reliability engineer has the task of assessing the probability of a plant operator failing to carry out the task of isolating a plant bypass route as required by procedure. However, the operator is fairly inexperienced in fulfilling this task and therefore typically does not follow the correct procedure; the individual is therefore unaware of the hazards created when the task is carried out

Assumptions There are various assumptions that should be considered in the context of the situation:

the operator is working a shift in which he is in his 7th hour. there is talk circulating the plant that it is due to close down it is possible for the operator's work to be checked at any time local management aim to keep the plant open despite a desperate need for re-vamping and maintenance work; if the plant is closed down for a short period, if the problems are unattended, there is a risk that it may remain closed permanently.

Method A representation of this situation using the HEART methodology would be done as follows: From the relevant tables it can be established that the type of task in this situation is of the type (F) which is defined as 'Restore or shift a system to original or new state following procedures, with some checking'. This task type has the proposed nominal human unreliability value of 0.003. Other factors to be included in the calculation are provided in the table below:

Result The final calculation for the normal likelihood of failure can therefore be formulated as:

0.003 x 1.8 x 6.0 x 3.4 x 2.2 x 1.12 = 0.27

Advantages HEART is very quick and straightforward to use and also has a small demand for resource usage The technique provides the user with useful suggestions as to how to reduce the occurrence of errors It provides ready linkage between Ergonomics and Process Design, with reliability improvement measures being a direct conclusion which can be drawn from the assessment procedure. It allows cost benefit analyses to be conducted It is highly flexible and applicable in a wide range of areas which contributes to the popularity of its use

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Worked examples

Example 1 — a first encounter with Human error assessment and reduction technique

Start with the simplest possible case. Write down what Human error assessment and reduction technique claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Human error assessment and reduction technique before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Human error assessment and reduction technique ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Human error assessment and reduction technique

In research: Human error assessment and reduction technique appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Human error assessment and reduction technique in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Human error assessment and reduction technique is common in secondary-school and first-year university syllabi. It links to neighbouring topics Human reliability, so understanding it makes those chapters shorter.
In everyday life: Look for Human error assessment and reduction technique outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Human error assessment and reduction technique in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Human error assessment and reduction technique means in your own words.
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Frequently asked questions

What is Human error assessment and reduction technique in simple terms?

Why does Human error assessment and reduction technique matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Human error assessment and reduction technique?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Human error assessment and reduction technique.